如何在 mongoose 中将 ObjectId 设置为数据类型 [英] How to set ObjectId as a data type in mongoose

问题描述

在 mongoHQ 和 mongoose 上使用 node.js、mongodb.我正在为类别设置架构.我想使用文档 ObjectId 作为我的 categoryId.

Using node.js, mongodb on mongoHQ and mongoose. I'm setting a schema for Categories. I would like to use the document ObjectId as my categoryId.

var mongoose = require('mongoose');

var Schema = mongoose.Schema,
    ObjectId = Schema.ObjectId;
var Schema_Category = new Schema({
    categoryId  : ObjectId,
    title       : String,
    sortIndex   : String
});

然后我跑

var Category = mongoose.model('Schema_Category');
var category = new Category();
category.title = "Bicycles";
category.sortIndex = "3";

category.save(function(err) {
  if (err) { throw err; }
  console.log('saved');
  mongoose.disconnect();     
});

请注意，我没有为 categoryId 提供值.我假设 mongoose 将使用模式来生成它，但文档具有通常的_id"而不是categoryId".我做错了什么?

Notice that I don't provide a value for categoryId. I assumed mongoose will use the schema to generate it but the document has the usual "_id" and not "categoryId". What am I doing wrong?

推荐答案

与传统的 RBDM 不同，mongoDB 不允许您定义任何随机字段作为主键，所有标准文档都必须存在 _id 字段.

Unlike traditional RBDMs, mongoDB doesn't allow you to define any random field as the primary key, the _id field MUST exist for all standard documents.

因此，创建单独的 uuid 字段没有意义.

For this reason, it doesn't make sense to create a separate uuid field.

在 mongoose 中，ObjectId 类型不用于创建新的 uuid，而是主要用于引用其他文档.

In mongoose, the ObjectId type is used not to create a new uuid, rather it is mostly used to reference other documents.

这是一个例子:

var mongoose = require('mongoose');

var Schema = mongoose.Schema,
    ObjectId = Schema.ObjectId;
var Schema_Product = new Schema({
    categoryId  : ObjectId, // a product references a category _id with type ObjectId
    title       : String,
    price       : Number
});

如您所见，使用 ObjectId 填充 categoryId 没有多大意义.

As you can see, it wouldn't make much sense to populate categoryId with a ObjectId.

但是，如果您确实想要一个命名良好的 uuid 字段，mongoose 提供了允许您代理(引用)字段的虚拟属性.

However, if you do want a nicely named uuid field, mongoose provides virtual properties that allow you to proxy (reference) a field.

检查一下:

var mongoose = require('mongoose');

var Schema = mongoose.Schema,
    ObjectId = Schema.ObjectId;
var Schema_Category = new Schema({
    title       : String,
    sortIndex   : String
});

Schema_Category.virtual('categoryId').get(function() {
    return this._id;
});

所以现在，每当您调用 category.categoryId 时，mongoose 只会返回 _id.

So now, whenever you call category.categoryId, mongoose just returns the _id instead.

您还可以创建一个set"方法，以便您可以设置虚拟属性，请查看此链接了解更多信息

You can also create a "set" method so that you can set virtual properties, check out this link for more info

这篇关于如何在 mongoose 中将 ObjectId 设置为数据类型的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！